The present invention relates to systems and methods for building three-dimensional (3D) objects in digital manufacturing systems. In particular, the present invention relates to high-temperature, extrusion-based digital manufacturing systems for building 3D object metal-based alloys.
An extrusion-based digital manufacturing system (e.g., fused deposition modeling systems developed by Stratasys, Inc., Eden Prairie, Minn.) is used to build a 3D object from a computer-aided design (CAD) model in a layer-by-layer manner by extruding a flowable modeling material. The modeling material is extruded through an extrusion tip carried by an extrusion head, and is deposited as a sequence of roads on a substrate in an x-y plane. The extruded modeling material fuses to previously deposited modeling material, and solidifies upon a drop in temperature. The position of the extrusion head relative to the substrate is then incremented along a z-axis (perpendicular to the x-y plane), and the process is then repeated to form a 3D object resembling the CAD model.
Movement of the extrusion head with respect to the substrate is performed under computer control, in accordance with build data that represents the 3D object. The build data is obtained by initially slicing the CAD model of the 3D object into multiple horizontally sliced layers. Then, for each sliced layer, the host computer generates a build path for depositing roads of modeling material to form the 3D object.
In fabricating 3D objects by depositing layers of modeling material, supporting layers or structures are typically built underneath overhanging portions or in cavities of objects under construction, which are not supported by the modeling material itself. A support structure may be built utilizing the same deposition techniques by which the modeling material is deposited. The host computer generates additional geometry acting as a support structure for the overhanging or free-space segments of the 3D object being formed. Support material is then deposited from a second nozzle pursuant to the generated geometry during the build process. The support material adheres to the modeling material during fabrication, and is removable from the completed 3D object when the build process is complete.
A common interest of consumers in the industry of digital manufacturing is to increase the physical properties of the 3D objects, such as part strengths and durability. One category of materials that could provide such increased physical properties include metal-based alloys. For example, 3D objects built from high-strength metals may exhibit tensile strengths that are substantially greater than those of industrial thermoplastic materials. However, the extrusion of metal-based alloys poses several issues for digital manufacturing. For example, the extrusion of metal-based alloys requires high operating temperatures, which may undesirably affect performance of current digital manufacturing systems. Furthermore, heating a metal-based alloy to a temperature above its liquidus temperature may prevent the alloy from having a sufficient viscosity for extrusion, and may undesirably affect its grain structure upon re-solidification (e.g., dendrite formation). Thus, there is an ongoing need for systems and methods for build 3D objects from metal-based alloys with digital manufacturing techniques.